Fig. 3

Scatterplots of the CTV volume, CTV D98, and presence or absence of local recurrence. Blue circles indicate tumor control cases and red circles indicate tumor recurrence cases. A red circle surrounded by a square indicates a case of local recurrence more than five years after C-ion RT, and blue circles surrounded by a triangle indicate cases of prescribed dose of 52.8 Gy (RBE) of C-ion RT. CTV, clinical target volume; RBE, relative biological effectiveness